1. Field of the Invention
The present invention relates generally to a rights expression manipulation system. In particular, the present invention is directed to systems and methods for creating, modifying, parsing, interpreting and validating licenses and/or rights expressions statements using templates which may or may not include tokens.
2. Discussion of the Related Art
Electronically distributing resources or content is developing into a lucrative industry. The term “content” is used broadly herein and includes digital works, such as music, audio files, text files, books, reports, video, multimedia, pictures, executable code, or any combination thereof. Controlling access to content is important when distributing them over inherently insecure networks and infrastructures, such as the Internet, although access control may be also desired in other settings. Failure to control resource access can result in unabated intellectual property right infringement and unrealized profits resulting from lost potential sales. Systems have been developed to help reduce these losses thereby enabling content owners to protect and profit from their digital content. Such systems are utilized to specify the usage rights for content or other things and to enforce the usage rights.
Various implementations of Rights Management Systems and rights associated with digital content are known as disclosed by U.S. Pat. Nos. 5,629,980, 5,634,012, 5,638,443, and No.5,715,403. Hence, the details of Rights Management Systems are not discussed specifically herein. As evident from these references, a Rights Management system can take many forms, and can employ varying levels of complexity depending on the security required, the nature of the thing being managed, the complexity of associated rights and conditions, volume and other factors. For example, Rights Management systems have been used to enable the secure distribution of digital media content over the Internet. Examples of such systems and associated paradigms are Pay-per-view, Subscription, and Superdistribution, as well as others. A Pay-per-view paradigm may require the user to pay a fee each time content is viewed. A Subscription paradigm may allow subscribers who pay monthly to download a number of songs per month. A Superdistribution paradigm may encourage the free and widespread distribution of digital content, such as audio or video clips, that can only be opened a limited number of times.
FIG. 1 illustrates an exemplary rights management (RM) system 100 and the associated workflow that can be used to distribute digital content. Typically, when a user goes through an activation process, information is exchanged between activation server 102 and client application 106, and is downloaded and installed in client application 106. Client application 106 serves as a tamper resistant security component and contains the set of public and private keys 104 that are issued by activation server 102 as well as other components such as any necessary engine for parsing or rendering protected content 108.
The RM system 100 also includes a content preparation application 103 that protects clear content 101 through encryption or other protective mechanisms to thereby provide protected content 108. The content preparation application 103 also specifies usage rights in a rights label 110 that is associated with protected content 108. The rights label 110 specifies usage rights that are available to an end-user when corresponding conditions are satisfied. A rights expression language (“REL”), such as XrML™, may be used to specify the rights and conditions set forth in the rights label 110. The rights label 110 and the appropriate encryption key that was used to encrypt the clear content 101 is then provided to the license server 112.
The license server 112 manages the encryption keys and issues license 114 that allows exercise of usage rights. For example, rights label 110 may include usage rights for viewing protected content 108 upon payment of a fee of five dollars, and viewing or printing protected content 108 upon payment of a fee of ten dollars. Client application 106 interprets and enforces the usage rights that have been specified in license 114 to provide clear content 116 that may be used by the end user.
The components and modules of the RM system 100 can be located in one or more than one device. For example, the activation server 102 and the license server 112 could be the same server or other device, or plural separate devices. The protected content 108 may be any type of content including a document, image, audio file, video file, etc. Further details of RM systems are set forth in further detail in the references noted above, and consequently, are not discussed specifically herein.
Thus, RM systems not only protect content, but also enable content owners to manage the sale and use of their content by means of licenses. Licenses include rights expressions written in a REL for articulating usage rights and to associate usage rights to content. Licenses may be specified for different stages during the life cycle of digital content. For example, when digital content is released to a distributor, licenses may be specified by content owners to limit distribution of the digital content to a particular region or a period of time, or to restrict how content may be repackaged. Of course, licenses themselves must be protected as well since they are a controlling facet determinative of how content is used. In this regard, licenses are typically digitally signed by the issuers so that their integrity and authenticity may be verified before being interpreted.
A license typically includes a grant element, a principal element, a right element, a resource element, and optionally, a condition element. In particular, a license contains one or more grant elements which defines the details of the usage rights granted. The one or more grant elements may specify a principal element, a rights element, a resource element and, optionally, a condition element. The principal element identifies a principal, such as a user, or a group of principals who is/are granted the right to access or use the protected resources, while the rights element names a specific right (e.g., play, view, print, execute, copy) to be given to the principal with regards to accessing or using the protected resources. The resource element specifies the protected resources, and the optional condition element specifies any conditions that are imposed on the right to use the protected resource.
A license is typically embodied as a rights expression. A rights expression is a syntactically and semantically correct language construct, based on a defined grammar, to convey rights information. As noted, an example of an REL is XrML™. It is important to note that the term “rights expression,” as used herein, should not be limited to licenses in particular, but refers to any expressions that may be used by the RM system to convey information. Thus, the term “rights expression” and derivatives thereof as used herein generally refers to expressions of licenses, license components and/or fragments, such as the grant element, principal element, right element, resource element, and/or condition element described above, as well as any other appropriate expressions. Moreover, rights expressions may be in a variety of different forms ranging from binary encoded sequences that target resource constrained applications to multi-level REL constructs that describe complex rights information for managed distribution of digital resources and rights granting paradigms, and including representations by symbols, objects, colors or other representations that are undetectable by human senses but which can be detected by machines.